Photovoltaic cell and preparation method thereof

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a preparation method thereof, and the preparation method comprises the steps: providing a cell piece body which comprises a substrate with a first surface and a second surface opposite to each other, a first aluminum oxide layer located on the first surface, and a second aluminum oxide layer located on the second surface; irradiating at least one of the first surface and the second surface with first light so as to carry out first photo-thermal annealing treatment on the battery piece body; carrying out laser enhanced contact processing on the battery piece body; irradiating at least one of the first surface and the second surface with second light to perform second photo-thermal annealing treatment on the battery piece body; wherein the wavelength of the first light is larger than that of the second light, and the heating temperature of the first photo-thermal annealing treatment is larger than that of the second photo-thermal annealing treatment. The embodiment of the invention is at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a divisional application of the Chinese invention patent application with the application date of February 28, 2025, application number 202510231721.1, and invention name “Photovoltaic cells and their preparation methods”. Technical Field

[0003] The present disclosure relates to the field of photovoltaics, and in particular to a photovoltaic cell and a method for preparing the same. Background Art

[0004] As fossil fuels gradually deplete, photovoltaic cells are becoming increasingly popular as a new energy alternative. Photovoltaic cells convert sunlight into electricity. They utilize the principle of photovoltaics to generate charge carriers, which are then extracted using electrodes, facilitating efficient use of the electrical energy.

[0005] Current photovoltaic cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact), PERC cells (Passivated emitter and real cell) and heterojunction cells.

[0006] However, photovoltaic cells formed by different preparation methods have different photoelectric conversion efficiencies, and it is necessary to develop a preparation method that is more conducive to improving the photoelectric conversion efficiency of photovoltaic cells. Summary of the Invention

[0007] The embodiments of the present disclosure provide a photovoltaic cell and a method for preparing the same, which are at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0008] According to some embodiments of the present disclosure, on the one hand, the embodiments of the present disclosure provide a method for preparing a photovoltaic cell, including: providing a cell body, the cell body including a substrate having a first surface and a second surface relative to each other, a first aluminum oxide layer located on the first surface, and a second aluminum oxide layer located on the second surface; using a first light to irradiate at least one of the first surface and the second surface to perform a first photothermal annealing treatment on the cell body; then performing a laser enhanced contact treatment on the cell body; using a second light to irradiate at least one of the first surface and the second surface to perform a second photothermal annealing treatment on the cell body; wherein the wavelength of the first light is greater than the wavelength of the second light; and the heating temperature of the first photothermal annealing treatment is greater than the heating temperature of the second photothermal annealing treatment.

[0009] In some embodiments, as the second photothermal annealing treatment proceeds, the light intensity density of the second light gradually decreases or first gradually increases and then gradually decreases, or the heating temperature of the second photothermal annealing treatment gradually decreases or first gradually increases and then gradually decreases.

[0010] In some embodiments, only the first surface is irradiated in the step of performing the first photothermal annealing treatment, and only the second surface is irradiated in the step of performing the second photothermal annealing treatment. The treatment time of the first photothermal annealing treatment is 30s to 50s, and the treatment time of the second photothermal annealing treatment is 8s to 15s.

[0011] In some embodiments, only the first surface is irradiated in the step of performing the first photothermal annealing treatment, and only the first surface is irradiated in the step of performing the second photothermal annealing treatment. The treatment time of the first photothermal annealing treatment is 30s to 50s, and the treatment time of the second photothermal annealing treatment is 3s to 7s.

[0012] In some embodiments, in the step of performing the first photothermal annealing treatment, only the first surface is irradiated, and in the step of performing the second photothermal annealing treatment, both the first surface and the second surface are irradiated, the treatment time of the first photothermal annealing treatment is 30s to 50s, and the treatment time of the second photothermal annealing treatment is 6s to 10s.

[0013] In some embodiments, the step of performing the first photothermal annealing treatment includes at least irradiating the first surface with the first light; and / or, at least a portion of the surface of the second surface is a polished surface, and the step of performing the second photothermal annealing treatment includes at least irradiating the second surface with the second light.

[0014] In some embodiments, the step of performing the first photothermal annealing treatment includes: providing a first light source and a second light source, the first light source is used to irradiate the first surface, the second light source is used to irradiate the second surface, the first light includes a first sub-light provided by the first light source and a second sub-light provided by the second light source; and / or, the step of performing the second photothermal annealing treatment includes: providing a third light source and a fourth light source, the third light source is used to irradiate the first surface, the fourth light source is used to irradiate the second surface, the second light includes a third sub-light provided by the third light source and a fourth sub-light provided by the fourth light source.

[0015] In some embodiments, at least one of the wavelength, light intensity density, and irradiation time of the light provided by the first light source and the second light source is different; and / or at least one of the wavelength, light intensity density, and irradiation time of the light provided by the third light source and the fourth light source is different.

[0016] In some embodiments, the light intensity density provided by the first light source is smaller than the light intensity density provided by the second light source; and / or the light intensity density provided by the third light source is smaller than the light intensity density provided by the fourth light source.

[0017] In some embodiments, the light intensity density provided by the first light source is 4 kW / m 2 ~8kW / m 2 The light intensity density provided by the second light source is 10kW / m 2 ~18kW / m 2 .

[0018] In some embodiments, the step of providing the battery cell body also includes: forming a first passivation layer on the side of the first aluminum oxide layer away from the first surface; and / or, forming a second passivation layer on the side of the second aluminum oxide layer away from the second surface; wherein the first passivation layer and / or the second passivation layer includes at least one of a silicon nitride layer, a silicon oxynitride layer or a silicon oxide layer.

[0019] In some embodiments, the wavelength of the first light is 800 nm to 1000 nm, and the wavelength of the second light is 365 nm to 400 nm.

[0020] According to some embodiments of the present disclosure, another aspect of the present disclosure further provides a photovoltaic cell, comprising: a photovoltaic cell formed according to any one of the preparation methods described above.

[0021] The technical solution provided by the embodiments of the present disclosure has at least the following advantages:

[0022] On the one hand, the wavelength of the first light used in the first photothermal annealing treatment is longer than that of the second light used in the second photothermal annealing treatment, and the photon energy of the first light is greater, which is conducive to deep activation of the first aluminum oxide layer and / or the second aluminum oxide layer, for example, increasing the hydrogen ion content in the first aluminum oxide layer and / or the second aluminum oxide layer, thereby improving the passivation effect of the first aluminum oxide layer and / or the second aluminum oxide layer on the surface of the substrate. On the other hand, the wavelength of the second light used in the second photothermal annealing treatment is shorter than that of the first light used in the first photothermal annealing treatment, and the second light is insufficient to break the silicon-hydrogen bond on the surface of the substrate. The second light is incident on the shallow surface of the photovoltaic cell, activating the first aluminum oxide layer and / or the second aluminum oxide layer, which is conducive to improving the contact performance between the electrode and the substrate, for example, reducing the probability of metal recombination between the electrode and the substrate. On the other hand, performing the first photoannealing treatment and the second photoannealing treatment before and after the laser enhanced contact treatment is conducive to improving the lifetime of minority carriers. In this way, the combined effect of multiple aspects is conducive to improving the photoelectric conversion efficiency of the final photovoltaic cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of a partial cross-sectional structure of a cell body in a method for preparing a photovoltaic cell provided in one embodiment of the present disclosure;

[0025] Figure 2 This is a schematic diagram of another partial cross-sectional structure of a cell body in the method for preparing a photovoltaic cell provided in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] As known from the background art, the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0027] The present disclosure provides a photovoltaic cell and a method for preparing the same. In the preparation method, on the one hand, the wavelength of the first light used in the first photothermal annealing treatment is longer than that of the second light used in the second photothermal annealing treatment, so the photon energy of the first light is greater, which is conducive to deep activation of the first aluminum oxide layer and / or the second aluminum oxide layer, for example, increasing the hydrogen ion content in the first aluminum oxide layer and / or the second aluminum oxide layer to improve the passivation effect of the first aluminum oxide layer and / or the second aluminum oxide layer on the surface of the substrate; on the other hand, the wavelength of the second light used in the second photothermal annealing treatment is shorter than that of the first light used in the first photothermal annealing treatment, so the second light is insufficient to break the silicon-hydrogen bond on the surface of the substrate. The second light is incident on the shallow surface of the photovoltaic cell and activates the first aluminum oxide layer and / or the second aluminum oxide layer, which is conducive to improving the contact performance between the electrode and the substrate, for example, reducing the metal recombination probability between the electrode and the substrate; on the other hand, the first photoannealing treatment and the second photoannealing treatment are performed before and after the laser enhanced contact treatment, which is conducive to improving the lifetime of minority carriers. In this way, the combined effect of multiple aspects is conducive to improving the photoelectric conversion efficiency of the photovoltaic cell finally prepared.

[0028] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present disclosure, "plurality" means more than two, unless otherwise specifically defined.

[0029] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of an association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0031] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0032] In the description of the embodiments of the present disclosure, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0033] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and they can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present disclosure based on specific circumstances.

[0034] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component can be "directly" located on the surface of the other component, or a third component can be present between the two components. Conversely, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0035] In the description of the embodiments of the present disclosure, when a component is referred to as "including" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component can be present between them. In addition, when a component such as a layer, film, region, or plate is "directly on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located between them.

[0036] The terms used herein in the description of the various embodiments are intended only to describe the specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is intended to include the plural form unless the context clearly indicates otherwise. A component includes a layer, film, region, or plate.

[0037] The following describes various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present disclosure to help readers better understand the embodiments of the present disclosure. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can be implemented.

[0038] An embodiment of the present disclosure provides a method for preparing a photovoltaic cell. The method for preparing a photovoltaic cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0039] refer to Figure 1 or Figure 2 The preparation method of a photovoltaic cell includes the following steps: providing a cell body 100, the cell body 100 including a substrate 101 having a first surface 111 and a second surface 121 opposite to each other, a first aluminum oxide layer 102 located on the first surface 111, and a second aluminum oxide layer 103 located on the second surface 121; using a first light to irradiate at least one of the first surface 111 and the second surface 121 to perform a first photothermal annealing treatment on the cell body 100; then performing a laser enhanced contact treatment on the cell body 100; using a second light to irradiate at least one of the first surface 111 and the second surface 121 to perform a second photothermal annealing treatment on the cell body 100; wherein the wavelength of the first light is greater than the wavelength of the second light.

[0040] in, Figure 1 A schematic diagram of a partial cross-sectional structure of a cell body in a method for preparing a photovoltaic cell provided in one embodiment of the present disclosure; Figure 2 This is a schematic diagram of another partial cross-sectional structure of a cell body in the method for preparing a photovoltaic cell provided in one embodiment of the present disclosure.

[0041] It is worth noting that the first photothermal annealing treatment and the second photothermal annealing treatment can respectively activate the first aluminum oxide layer and / or the second aluminum oxide layer to enhance the passivation effect of the first aluminum oxide layer and / or the second aluminum oxide layer on the substrate. Specifically, on the one hand, compared with the second light used in the second photothermal annealing treatment, the wavelength of the first light used in the first photothermal annealing treatment is larger, and the photon energy of the first light is larger, which is conducive to deep activation of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, such as increasing the content of hydrogen ions in the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, so as to enhance the passivation effect of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 on the surface of the substrate 101, such as increasing the probability of hydrogen ions compounding with surface defects of the substrate 101, so as to achieve passivation of the surface of the substrate 101. On the other hand, compared with the first light used in the first photothermal annealing treatment, the wavelength of the second light used in the second photothermal annealing treatment is smaller, and the second light is not enough to break the silicon-hydrogen bond on the surface of the substrate 101. The second light is incident on the shallow surface of the photovoltaic cell, activating the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, which is beneficial to improving the contact performance between the electrode and the substrate 101, such as reducing the probability of metal recombination between the electrode and the substrate 101; on the other hand, performing the first photoannealing treatment and the second photoannealing treatment before and after the laser enhanced contact treatment is beneficial to improving the lifetime of minority carriers. In this way, the combined effect of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell finally prepared. In some examples, the photoelectric conversion efficiency of the photovoltaic cell formed by the method for preparing a photovoltaic cell provided by an embodiment of the present disclosure can be improved by approximately 0.03% to 0.05%.

[0042] The following describes in detail each step of the method for preparing a photovoltaic cell according to an embodiment of the present disclosure:

[0043] In some embodiments, reference Figure 2 The step of providing the battery cell body 100 may further include: forming a first passivation layer 104 on a side of the first aluminum oxide layer 102 away from the first surface 111; and / or forming a second passivation layer 105 on a side of the second aluminum oxide layer 103 away from the second surface 121; wherein the first passivation layer 104 and / or the second passivation layer 105 may include at least one of a silicon nitride layer, a silicon oxynitride layer or a silicon oxide layer.

[0044] It is worth emphasizing that the first photothermal annealing treatment and the second photothermal annealing treatment can respectively activate the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 to enhance the passivation effect of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 on the substrate 101. Similarly, the first photothermal annealing treatment and the second photothermal annealing treatment can respectively activate the first passivation layer 104 and / or the second passivation layer 105, for example, to increase the content of ions that can play a passivating effect in the first passivation layer 104 and / or the second passivation layer 105, thereby further increasing the probability that the surface defects of the substrate 101 are passivated by ions, thereby enhancing the overall passivation effect of the photovoltaic cell.

[0045] It should be noted that Figure 2 In the example, a first passivation layer 104 is formed on the side of the first aluminum oxide layer 102 away from the first surface 111, and a second passivation layer 105 is formed on the side of the second aluminum oxide layer 103 away from the second surface 121. In actual applications, the first passivation layer may be formed only on the side of the first aluminum oxide layer away from the first surface, or the second passivation layer may be formed only on the side of the second aluminum oxide layer away from the second surface.

[0046] In some embodiments, the step of providing the cell body 100 may further include: disposing electrode slurry on the cell body 100; and performing electrode metallization treatment on the electrode slurry to form an electrode on at least one of the first surface 111 and the second surface 121 (not shown in the figure).

[0047] In some examples, disposing the electrode paste on the cell body 100 may include disposing the electrode paste on the cell body 100 using a screen printing process, or disposing the electrode paste on the cell body 100 using an electroplating process. In some examples, the electrode paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0048] In some examples, the step of performing an electrode metallization process on the electrode slurry may include: performing a sintering process on the electrode slurry. In some examples, the electrode slurry contains a highly corrosive component such as glass. Thus, during the sintering process, the corrosive component will corrode the first aluminum oxide layer 102 and the first passivation layer 104, so that the final electrode is embedded in the first aluminum oxide layer 102 and the first passivation layer 104; and / or, during the sintering process, the corrosive component will corrode the second aluminum oxide layer 103 and the second passivation layer 105, so that the final electrode is embedded in the second aluminum oxide layer 103 and the second passivation layer 105.

[0049] In some embodiments, the material of the substrate 101 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be in a single crystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both single crystalline and amorphous states is referred to as a microcrystalline state). For example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0050] In other embodiments, the substrate 101 may be made of a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide, and the like.

[0051] In some embodiments, the substrate 101 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which may be at least one of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type dopant element, which may be at least one of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In).

[0052] In some embodiments, the wavelength of the first light used in the first photothermal annealing treatment may be 800 nm to 1000 nm. For example, the wavelength of the first light may be 810 nm, 820 nm, 830 nm, 840 nm, 850 nm, 860 nm, 870 nm, 880 nm, 890 nm, 900 nm, 910 nm, 920 nm, 930 nm, 940 nm, 950 nm, 960 nm, 970 nm, 980 nm, or 990 nm. The wavelength of the second light used in the second photothermal annealing treatment may be 365 nm to 400 nm. For example, the wavelength of the second light may be 370 nm, 372 nm, 375 nm, 376 nm, 378 nm, 380 nm, 383 nm, 385 nm, 386 nm, 390 nm, 392 nm, 395 nm, 396 nm, or 399 nm.

[0053] In some examples, the first light used in the first photothermal annealing process may be infrared light, and the second light used in the second photothermal annealing process may be ultraviolet light.

[0054] It is worth emphasizing that the surfaces of the cell body 100 irradiated by the first photothermal annealing treatment and the second photothermal annealing treatment may be only partially the same, completely the same, or completely different. Various irradiation situations are described in detail below.

[0055] In some embodiments, the step of performing the first photothermal annealing treatment at least includes using the first light to irradiate the first surface 111. In other words, the first light can irradiate only the first surface 111, or can irradiate the first surface 111 and the second surface 121 simultaneously.

[0056] In some embodiments, reference Figure 1 or Figure 2 , at least part of the surface of the second surface 121 is a polished surface, and the step of performing the second photothermal annealing treatment at least includes irradiating the second surface 121 with a second light. In other words, the second light can irradiate only the second surface 121, or can irradiate the second surface 121 and the first surface 111 at the same time. It is worth emphasizing that at least part of the surface of the second surface 121 is a polished surface, which is conducive to improving the uniformity of the second aluminum oxide layer 103 formed on the second surface 121, thereby balancing the passivation effect of each region of the second aluminum oxide layer 103 on the substrate 101 after irradiation with the second light, for example, the content of hydrogen ions in each region of the second aluminum oxide layer 103 after irradiation with the second light is almost uniformly increased, so that each region of the second aluminum oxide layer 103 has a good passivation effect on the substrate 101. It should be noted that, Figure 1 and Figure 2 In the example, the entire second surface 121 is a polished surface. In actual applications, only the area of ​​the second surface facing the electrode can be a polished surface, and the area not shielded by the electrode can be a velvet surface or have other surface texture structures to enhance the second surface's absorption effect on incident light and increase the photoelectric conversion efficiency of the photovoltaic cell.

[0057] In other embodiments, the first light may only illuminate the second surface, and / or the second light may only illuminate the first surface.

[0058] In some embodiments, reference Figure 1 or Figure 2 The first surface 111 may be a velvet surface, which can improve the absorption efficiency of the first surface 111 for incident light. In some examples, the velvet surface may be a pyramid velvet surface. Pyramid velvet is a common velvet surface that not only reduces the reflectivity of the first surface but also forms a light trap, thereby enhancing the absorption of incident light by the first surface and increasing the photoelectric conversion efficiency of the photovoltaic cell.

[0059] It should be noted that in some embodiments, the cell body 100 is a single-sided cell, and the first surface 111 can be considered the front surface of the cell body 100, that is, the first surface 111 can serve as the light-receiving surface for receiving incident light, and the second surface 121 can serve as the backlight surface. In other embodiments, the cell body 100 is a bifacial cell, and both the first surface 111 and the second surface 121 can serve as light-receiving surfaces, and can both be used to receive incident light. It is understood that the backlight surface described in one embodiment of the present disclosure can also receive incident light, but the degree of reception of incident light is weaker than that of the light-receiving surface, and therefore is defined as the backlight surface.

[0060] It is worth noting that for the second photothermal annealing treatment, compared with the improvement of the passivation effect of the substrate 101 after only irradiating the second surface 121 with the second light, the improvement of the passivation effect of the substrate 101 after irradiating both the first surface 111 and the second surface 121 with the second light is better; compared with the improvement of the passivation effect of the substrate 101 after only irradiating the first surface 111 with the second light, the improvement of the passivation effect of the substrate 101 after irradiating the second surface 121 with the second light is better.

[0061] In some embodiments, the step of performing the first photothermal annealing process may include providing a first light source and a second light source, wherein the first light source is used to illuminate the first surface 111, and the second light source is used to illuminate the second surface 121, wherein the first light comprises a first sub-light provided by the first light source and a second sub-light provided by the second light source. In some examples, the first light source and the second light source may be located on opposite sides of the cell body 100 along the thickness direction, i.e., the first light source is located on a side of the first surface 111 away from the second surface 121, and the second light source is located on a side of the second surface 121 away from the first surface 111.

[0062] In some embodiments, the step of performing the second optical thermal annealing treatment may include providing a third light source and a fourth light source, wherein the third light source is used to illuminate the first surface 111, and the fourth light source is used to illuminate the second surface 121, and the second light includes a third sub-light provided by the third light source and a fourth sub-light provided by the fourth light source. In some examples, the third light source and the fourth light source may be located on opposite sides of the cell body 100 along the thickness direction, that is, the third light source is located on a side of the first surface 111 away from the second surface 121, and the fourth light source is located on a side of the second surface 121 away from the first surface 111.

[0063] It should be noted that when the first light source and the second light source are provided simultaneously in the first photothermal annealing treatment, the third light source and the fourth light source can be provided simultaneously in the second photothermal annealing treatment, or only one of the third light source and the fourth light source can be provided. In this way, at least one of the first aluminum oxide layer 102 and the second aluminum oxide layer 103 is subjected to the second photothermal annealing treatment after the first photothermal annealing treatment, so as to undergo two activations; when the first light source and one of the second light source are provided in the first photothermal annealing treatment, the third light source and the fourth light source can be provided simultaneously in the second photothermal annealing treatment, or only one of the third light source and the fourth light source can be provided.

[0064] In some examples, the various operating parameters of the first light source and the second light source, such as light wavelength, light intensity density, and irradiation time, can be respectively the same, so that the first photothermal annealing treatment creates the same photothermal annealing environment for the first surface 111 and the second surface 121; in other examples, at least one of the light wavelength, light intensity density, and irradiation time provided by the first light source and the second light source can be different, so that the first photothermal annealing treatment creates different photothermal annealing environments for the first surface 111 and the second surface 121.

[0065] In some examples, the various operating parameters of the third light source and the fourth light source, such as light wavelength, light intensity density, and irradiation time, can be respectively the same, so that the second photothermal annealing treatment provides the first surface 111 and the second surface 121 with the same photothermal annealing environment; in other examples, at least one of the light wavelength, light intensity density, and irradiation time provided by the third light source and the fourth light source is different, so that the second photothermal annealing treatment provides the first surface 111 and the second surface 121 with different photothermal annealing environments.

[0066] The design of various operating parameters of the first light source, the second light source, the third light source and the fourth light source is described in detail below.

[0067] In some examples, the light intensity density provided by the first light source may be less than the light intensity density provided by the second light source. In other words, the illumination intensity of the first sub-light on the first surface 111 is lower than the illumination intensity of the second sub-light on the second surface 121, which is conducive to making the photon energy received per unit area on the second surface 121 higher than the photon energy received per unit area on the first surface 111.

[0068] It should be noted that compared with the first surface 111 serving as the light-receiving surface, the second surface 121 serving as the backlight surface generally has a lower light utilization rate. For example, a polysilicon layer may be provided between the substrate 101 and the second aluminum oxide layer 103. The polysilicon layer will reduce the absorption of photon energy by the substrate 101. Therefore, designing the light intensity density provided by the first light source to be smaller than the light intensity density provided by the second light source is beneficial to compensating for the low light utilization rate of the second surface 121 in the first photothermal annealing step, so as to ensure a good passivation effect of the second light source on the second surface 121.

[0069] In some examples, the light intensity density provided by the third light source may be less than the light intensity density provided by the fourth light source. In other words, the illumination intensity of the third sub-light on the first surface 111 is lower than the illumination intensity of the fourth sub-light on the second surface 121, which is conducive to making the photon energy received per unit area on the second surface 121 higher than the photon energy received per unit area on the first surface 111.

[0070] It should be noted that compared with the first surface 111 serving as the light-receiving surface, the second surface 121 serving as the backlight surface generally has a lower light utilization rate. For example, a polysilicon layer may be provided between the substrate 101 and the second aluminum oxide layer 103. The polysilicon layer will reduce the absorption of photon energy by the substrate 101. Therefore, designing the light intensity density provided by the third light source to be smaller than the light intensity density provided by the fourth light source is beneficial to compensating for the low light utilization rate of the second surface 121 in the second photothermal annealing step, so as to ensure a good passivation effect of the fourth light source on the second surface 121.

[0071] It is worth noting that in actual applications, when the light intensity density provided by the first light source is less than the light intensity density provided by the second light source, the light intensity density provided by the third light source can be less than, equal to, or greater than the light intensity density provided by the fourth light source; and when the light intensity density provided by the third light source is less than the light intensity density provided by the fourth light source, the light intensity density provided by the first light source can be less than, equal to, or greater than the light intensity density provided by the second light source. In other words, the relationship between the light intensity densities provided by the first and second light sources, and the relationship between the light intensity densities provided by the third and fourth light sources, can be flexibly adjusted according to specific needs.

[0072] In one example, in the first photothermal annealing step, when both the first surface 111 and the second surface 121 are irradiated, the light intensity density provided by the first light source can be 4 kW / m 2 ~8kW / m 2 , for example, it can be 4.5kW / m 2 , 5kW / m 2 5.5kW / m 2 , 6kW / m 2 、6.5kW / m 2 , 7kW / m 2or 7.5kW / m 2 The light intensity density provided by the second light source can be 10kW / m 2 ~18kW / m 2 , for example, it can be 10.5kW / m 2 、11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 、13kW / m 2 、13.5kW / m 2 、14kW / m 2 、14.5kW / m 2 、15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2 、17kW / m 2 or 17.5kW / m 2 wait.

[0073] In one example, in the second photothermal annealing step, when both the first surface 111 and the second surface 121 are irradiated, the light intensity density provided by the third light source may be 4 kW / m 2 ~8kW / m 2 , for example, it can be 4.5kW / m 2 , 5kW / m 2 5.5kW / m 2 , 6kW / m 2 、6.5kW / m 2 , 7kW / m 2 or 7.5kW / m 2 The light intensity density provided by the fourth light source can be 10kW / m 2 ~18kW / m 2 , for example, it can be 10.5kW / m 2 、11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 、13kW / m 2 、13.5kW / m 2 、14kW / m 2 、14.5kW / m 2 、15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2、17kW / m 2 or 17.5kW / m 2 wait.

[0074] In some embodiments, in the first photothermal annealing step, only the first surface 111 is irradiated, and in the second photothermal annealing step, at least one of the first surface 111 and the second surface 121 is irradiated. The light intensity density of the first light can be 10 kW / m 2 ~20kW / m 2 The light intensity density of the second light is 6kW / m 2 ~18kW / m 2 It should be noted that the first light only includes the first sub-light for irradiating the first surface 111, and the second light includes at least one of the third sub-light for irradiating the first surface 111 and the fourth sub-light for irradiating the second surface 121, and the light intensity density of the third sub-light and the fourth sub-light can both be 6kW / m 2 ~18kW / m 2 .

[0075] In some examples, the light intensity density of the first light can be 10.5 kW / m 2 、11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 、13kW / m 2 、13.5kW / m 2 、14kW / m 2 、14.5kW / m 2 、15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2 、17kW / m 2 、17.5kW / m 2 、18kW / m 2 、18.5kW / m 2 、19kW / m 2 or 19.5kW / m 2 wait.

[0076] In some examples, the light intensity density of the second light can be 6.5 kW / m 2 , 7kW / m 2 、10.5kW / m 2 , 7.5kW / m 2 , 8kW / m 2 、8.5kW / m 2 , 9kW / m2 , 9.5kW / m 2 、10kW / m 2 、10.5kW / m 2 、11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 、13kW / m 2 、13.5kW / m 2 、14kW / m 2 、14.5kW / m 2 、15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2 、17kW / m 2 or 17.5kW / m 2 wait.

[0077] In some examples, the processing time of the first photothermal annealing treatment can be 30s to 50s, for example, it can be 31s, 32s, 33s, 34s, 35s, 36s, 37s, 38s, 39s, 40s, 41s, 42s, 43s, 44s, 45s, 46s, 47s, 48s or 49s, etc.; the processing time of the second photothermal annealing treatment is 2s to 15s, for example, it can be 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s or 14s, etc.

[0078] In some examples, when only the first surface 111 is irradiated in the first photothermal annealing step and only the second surface 121 is irradiated in the second photothermal annealing step, the processing time of the first photothermal annealing can be 30s to 50s, and the processing time of the second photothermal annealing can be 8s to 15s.

[0079] In other examples, when only the first surface 111 is irradiated in the first photothermal annealing step and only the first surface 111 is irradiated in the second photothermal annealing step, the processing time of the first photothermal annealing can be 30s to 50s, and the processing time of the second photothermal annealing is 3s to 7s.

[0080] In some other examples, when only the first surface 111 is irradiated in the first photothermal annealing treatment step, and both the first surface 111 and the second surface 121 are irradiated in the second photothermal annealing treatment step, the treatment time of the first photothermal annealing treatment can be 30s to 50s, and the treatment time of the second photothermal annealing treatment is 6s to 10s.

[0081] In the various embodiments described above, the heating temperature of the first photothermal annealing treatment may be greater than the heating temperature of the second photothermal annealing treatment. It is worth noting that, within a certain range, the higher the heating temperature of the photothermal annealing treatment, the more conducive it is to the diffusion of ions that can play a passivation effect to the substrate 101, thereby increasing the probability that the surface defects of the substrate 101 are passivated by ions. Based on this, the heating temperature of the first photothermal annealing treatment is designed to be greater than the heating temperature of the second photothermal annealing treatment. This is beneficial for achieving a better passivation effect on the substrate 101 with the help of the first photoannealing treatment while controlling the heating temperature of the second photothermal annealing treatment to be lower, thereby shortening the cooling time, so as to facilitate the subsequent timely IV (current-voltage) test of the prepared photovoltaic cell, thereby shortening the length of the equipment required to prepare the photovoltaic cell and increasing the life of the transmission belt.

[0082] In one example, the heating temperature of the first photothermal annealing treatment can be 240℃~300℃, for example, it can be 245℃, 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃ or 295℃, etc.; the heating temperature of the second photothermal annealing treatment can be 50℃~140℃, for example, it can be 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃ or 135℃, etc.

[0083] In the various embodiments described above, the step of performing the first photothermal annealing treatment may include: controlling the light intensity density of the first light to gradually change within the treatment time of the first photothermal annealing treatment, and / or controlling the heating temperature of the first photothermal annealing treatment to gradually change within the treatment time of the first photothermal annealing treatment.

[0084] It should be noted that controlling the intensity density of the first light to gradually change during the treatment time of the first photothermal annealing treatment may include the following three situations: as the first photothermal annealing treatment progresses, the intensity density of the first light gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. Controlling the heating temperature of the first photothermal annealing treatment to gradually change during the treatment time of the first photothermal annealing treatment may include the following three situations: as the first photothermal annealing treatment progresses, the heating temperature of the first photothermal annealing treatment gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. This helps to control the temperature of the photovoltaic cell surface and is less likely to cause contaminants on the transmission belt to adhere to the photovoltaic cell surface.

[0085] Among them, controlling the light intensity density of the first light to gradually decrease or first gradually increase and then gradually decrease, or controlling the heating temperature of the first photothermal annealing treatment to gradually decrease or first gradually increase and then gradually decrease, are both beneficial to shortening the cooling time, so as to facilitate the subsequent timely IV (current-voltage) test of the prepared photovoltaic cell, thereby facilitating the shortening of the equipment length required for preparing the photovoltaic cell and improving the life of the transmission belt.

[0086] In the various embodiments described above, the step of performing a second photothermal annealing treatment may include: controlling the light intensity density of the second light to gradually change within the treatment time of the second photothermal annealing treatment, and / or controlling the heating temperature of the second photothermal annealing treatment to gradually change within the treatment time of the second photothermal annealing treatment.

[0087] It should be noted that controlling the intensity density of the second light to gradually change during the treatment time of the second photothermal annealing treatment may include the following three situations: as the second photothermal annealing treatment progresses, the intensity density of the second light gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. Controlling the heating temperature of the second photothermal annealing treatment to gradually change during the treatment time of the second photothermal annealing treatment may include the following three situations: as the second photothermal annealing treatment progresses, the heating temperature of the second photothermal annealing treatment gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. This helps to control the temperature of the photovoltaic cell surface and is less likely to cause contaminants on the transmission belt to adhere to the photovoltaic cell surface.

[0088] Among them, controlling the light intensity density of the second light to gradually decrease or first gradually increase and then gradually decrease, or controlling the heating temperature of the second photothermal annealing treatment to gradually decrease or first gradually increase and then gradually decrease, are both beneficial to shortening the cooling time, so as to facilitate the subsequent timely IV (current-voltage) test of the prepared photovoltaic cell, thereby facilitating the shortening of the equipment length required for preparing the photovoltaic cell and improving the life of the transmission belt.

[0089] In some embodiments, a method for controlling the gradual change of the light intensity density of the first light during the processing time of the first photothermal annealing treatment includes: designing at least one of the first light source or the second light source to include multiple lamp groups connected in series, and adopting power control to gradually change the light intensity of the multiple lamp groups; a method for controlling the gradual change of the light intensity density of the second light during the processing time of the second photothermal annealing treatment includes: designing at least one of the third light source or the fourth light source to include multiple lamp groups connected in series, and adopting power control to gradually change the light intensity of the multiple lamp groups.

[0090] In some embodiments, laser-enhanced contact processing (LECP), which can be laser-assisted sintering (LAS), also known as laser-enhanced contact optimization (LECP), is used to improve the contact between electrodes and silicon wafers in photovoltaic cells. During LECP, a laser is used for non-destructive carrier injection. After LECP, the contact resistance between the electrodes and silicon wafer in the photovoltaic cell is significantly reduced, which helps increase the open-circuit voltage and short-circuit current of the photovoltaic cell.

[0091] In summary, the first photothermal annealing treatment and the second photothermal annealing treatment can respectively activate the first aluminum oxide layer and / or the second aluminum oxide layer to enhance the passivation effect of the first aluminum oxide layer and / or the second aluminum oxide layer on the substrate. Specifically, on the one hand, compared with the second light used in the second photothermal annealing treatment, the wavelength of the first light used in the first photothermal annealing treatment is larger, and the photon energy of the first light is larger, which is beneficial to deep activation of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, for example, increasing the content of hydrogen ions in the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 to enhance the passivation effect of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 on the surface of the substrate 101; on the other hand, compared with the second light used in the first photothermal annealing treatment, The wavelength of the second light used in the second photothermal annealing treatment is smaller, making it insufficient to break the silicon-hydrogen bonds on the surface of the substrate 101. The second light is incident on the shallow surface of the photovoltaic cell, activating the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, which helps improve the contact performance between the electrode and the substrate 101, for example, reducing the probability of metal recombination between the electrode and the substrate 101. Furthermore, performing the first and second photoannealing treatments before and after the laser-enhanced contact treatment helps improve the lifetime of minority carriers. In this way, the combined effect of these multiple factors helps improve the photoelectric conversion efficiency of the final photovoltaic cell.

[0092] Another embodiment of the present disclosure further provides a photovoltaic cell, which is prepared using the preparation method provided in the above embodiment. The photovoltaic cell provided in another embodiment of the present disclosure is described in detail below with reference to the accompanying drawings. It should be noted that parts that are identical or corresponding to the above embodiment are not described in detail here.

[0093] refer to Figure 1 or Figure 2 , the photovoltaic cell includes: a photovoltaic cell formed according to the preparation method provided in the above embodiment.

[0094] It is worth noting that the photovoltaic cell can be a cell with a passivation structure such as a TOPCON cell, a PERC cell, an IBC cell, or a heterojunction cell. The photovoltaic cell is formed according to the preparation method provided in the above embodiment, and the first and second photoannealing treatments are performed before and after the laser enhanced contact treatment, which is beneficial for improving the photoelectric conversion efficiency of the formed photovoltaic cell.

[0095] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present disclosure, and in actual applications, various changes may be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the scope of protection of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A method for preparing a photovoltaic cell, characterized in that: include: Providing a cell body, the cell body comprising a substrate having a first surface and a second surface opposite to each other, a first aluminum oxide layer located on the first surface, and a second aluminum oxide layer located on the second surface; irradiating at least one of the first surface and the second surface with a first light to perform a first photothermal annealing treatment on the cell body; Then, performing laser enhanced contact treatment on the battery cell body; irradiating at least one of the first surface and the second surface with a second light to perform a second photothermal annealing treatment on the cell body; The wavelength of the first light is greater than the wavelength of the second light; and the heating temperature of the first photothermal annealing treatment is greater than the heating temperature of the second photothermal annealing treatment.

2. The method for preparing a photovoltaic cell according to claim 1, wherein: As the second photothermal annealing treatment proceeds, the light intensity density of the second light gradually decreases or first gradually increases and then gradually decreases, or the heating temperature of the second photothermal annealing treatment gradually decreases or first gradually increases and then gradually decreases.

3. The method for preparing a photovoltaic cell according to claim 1, wherein: In the step of performing the first photothermal annealing treatment, only the first surface is irradiated, and in the step of performing the second photothermal annealing treatment, only the second surface is irradiated. The treatment time of the first photothermal annealing treatment is 30s to 50s, and the treatment time of the second photothermal annealing treatment is 8s to 15s.

4. The method for preparing a photovoltaic cell according to claim 1, wherein: In the step of performing the first photothermal annealing treatment, only the first surface is irradiated, and in the step of performing the second photothermal annealing treatment, only the first surface is irradiated. The treatment time of the first photothermal annealing treatment is 30s to 50s, and the treatment time of the second photothermal annealing treatment is 3s to 7s.

5. The method for preparing a photovoltaic cell according to claim 1, wherein: In the step of performing the first photothermal annealing treatment, only the first surface is irradiated, and in the step of performing the second photothermal annealing treatment, both the first surface and the second surface are irradiated. The treatment time of the first photothermal annealing treatment is 30s to 50s, and the treatment time of the second photothermal annealing treatment is 6s to 10s.

6. The method for preparing a photovoltaic cell according to claim 1, wherein: The step of performing the first photothermal annealing treatment includes at least irradiating the first surface with the first light; and / or, at least part of the surface of the second surface is a polished surface, and the step of performing the second photothermal annealing treatment includes at least irradiating the second surface with the second light.

7. The method for preparing a photovoltaic cell according to claim 1, wherein: The step of performing the first photothermal annealing treatment includes: providing a first light source and a second light source, wherein the first light source is used to illuminate the first surface, and the second light source is used to illuminate the second surface, and the first light includes a first sub-light provided by the first light source and a second sub-light provided by the second light source; and / or, The step of performing the second photothermal annealing treatment includes: providing a third light source and a fourth light source, the third light source is used to irradiate the first surface, the fourth light source is used to irradiate the second surface, and the second light includes a third sub-light provided by the third light source and a fourth sub-light provided by the fourth light source.

8. The method for preparing a photovoltaic cell according to claim 7, wherein: The first light source and the second light source provide light with at least one of different wavelengths, light intensity densities and irradiation times; and / or the third light source and the fourth light source provide light with at least one of different wavelengths, light intensity densities and irradiation times.

9. The method for preparing a photovoltaic cell according to claim 8, wherein: The light intensity density provided by the first light source is smaller than the light intensity density provided by the second light source; and / or the light intensity density provided by the third light source is smaller than the light intensity density provided by the fourth light source.

10. The method for preparing a photovoltaic cell according to claim 9, wherein: The light intensity density provided by the first light source is 4kW / m 2 ~8kW / m 2 The light intensity density provided by the second light source is 10kW / m 2 ~18kW / m 2 .

11. The method for preparing a photovoltaic cell according to claim 1, wherein: The step of providing the battery cell body further includes: forming a first passivation layer on a side of the first aluminum oxide layer away from the first surface; and / or, forming a second passivation layer on a side of the second aluminum oxide layer away from the second surface; The first passivation layer and / or the second passivation layer includes at least one of a silicon nitride layer, a silicon oxynitride layer or a silicon oxide layer.

12. The method for preparing a photovoltaic cell according to any one of claims 1 to 11, characterized in that: The wavelength of the first light is 800nm-1000nm, and the wavelength of the second light is 365nm-400nm.

13. A photovoltaic cell, characterized in that: include: A photovoltaic cell formed by the method for preparing a photovoltaic cell according to any one of claims 1 to 12.

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